In the prior art, systems used to unload portable containers of fluidizable material typically have consisted of a support frame structure, a hopper mounted on such structure, means for suspending the container on the support structure for gravity feeding material from the container into the hopper and a filter for capturing the products of material becoming airborne in the hopper as a result of the material flowing into the hopper. In such systems, it has been found that as a result of the positioning of the filter relative to the hopper, the filter media quickly become clogged, correspondingly decreasing the efficiency of the filter, and further that as a result of the positioning of the container being unloaded, a significant amount of the material being gravity fed from the container into the hopper, becomes airborne, not only contaminating the ambient atmosphere affecting the health of operating personnel but resulting in loss of material. It thus is the principal object of the present invention to provide such a system in which material unloaded from a portable container into a hopper will gravity flow freely and steadily, and particles of such material becoming airborne in the feeding process will be prevented from escaping into the ambient atmosphere, prevented from diminishing the effectiveness of the dust control equipment and captured to enhance productivity.